Low-temperature-slush-fluid producing apparatus

ABSTRACT

A low-temperature-slush-fluid producing apparatus capable of achieving an increased weight solidification rate of slush fluid is provided. A low-temperature-slush-fluid producing apparatus includes a slush-fluid producing unit that includes a heat exchanger having a heat-transfer surface and disposed in a liquid-phase low-temperature fluid L stored in a container and scraping means for scraping a solid-phase low-temperature fluid formed on a surface of the heat-transfer surface; and a cryogenic-fluid generating unit for supplying into the interior of the heat-transfer surface a cryogenic fluid having a lower temperature than the liquid-phase low-temperature fluid L stored in the container. The low-temperature-slush-fluid producing apparatus is configured so that the flow rate and temperature of the cryogenic fluid flowing into the interior of the heat-transfer surface and the rotational speed or reciprocating speed of the scraping means can be adjusted based on the particle size of the solid-phase low-temperature fluid scraped by the scraping means.

TECHNICAL FIELD

The present invention relates to a low-temperature-slush-fluid producingapparatus for producing a low-temperature slush fluid (for example,slush hydrogen (a sorbet-like mixture of solid hydrogen and liquidhydrogen that has a higher density and therefore a larger stored coolingcapacity than liquid hydrogen)).

BACKGROUND ART

One conventionally known apparatus for producing slush hydrogen isdisclosed in Non-patent Document 1.

Non-patent Document 1:

D. E. Daney, “HYDROGEN SLUSH PRODUCTION WITH A LARGE AUGER” (U.S.),Advanced in Cryogenic Engineering, Vol. 35

DISCLOSURE OF INVENTION

The slush-hydrogen producing apparatus disclosed in Non-patent Document1 above, however, has limited capability in terms of reducing theparticle size of solidified hydrogen; it has a problem in that theweight solidification rate of slush hydrogen (the proportion by weightof solidified hydrogen in liquid hydrogen) cannot be satisfactorilyincreased.

An object of the present invention, which has been made in light of theabove circumstances, is to provide a low-temperature-slush-fluidproducing apparatus capable of achieving an increased weightsolidification rate of slush fluid.

To solve the above problem, the present invention employs the followingsolutions.

A low-temperature-slush-fluid producing apparatus according to thepresent invention includes a slush-fluid producing unit that includes aheat exchanger having a heat-transfer surface and disposed in aliquid-phase low-temperature fluid stored in a container and scrapingmeans for scraping a solid-phase low-temperature fluid formed on asurface of the heat-transfer surface; and a cryogenic-fluid generatingunit for supplying into the interior of the heat-transfer surface acryogenic fluid having a lower temperature than the liquid-phaselow-temperature fluid stored in the container. The apparatus isconfigured so that the flow rate and temperature of the cryogenic fluidflowing into the interior of the heat-transfer surface and therotational speed or reciprocating speed of the scraping means can beadjusted based on the particle size of the solid-phase low-temperaturefluid scraped by the scraping means.

In this low-temperature-slush-fluid producing apparatus, for example, asshown in FIG. 1, the particle size of particles 22 of a low-temperaturefluid L scraped by a blade 13 a of an auger (scraping means) 13 can bereduced (finer particles can be formed) by adjusting (controlling) theamount of heat generated by a heater 6, the degree of valve opening of afirst valve 7, the degree of valve opening of a second valve 8, and therotational speed of a drive motor 19, thereby increasing the weightsolidification rate of slush fluid.

In addition, if such a slush fluid (slush hydrogen with an increasedweight solidification rate) is charged (supplied) into, for example, avehicle hydrogen storage tank installed in a vehicle that runs onhydrogen as a fuel, such as a fuel-cell powered vehicle or ahydrogen-fueled vehicle, it is possible to reduce evaporation ofhydrogen in the vehicle hydrogen storage tank and to improve theutilization efficiency of hydrogen.

In the above low-temperature-slush-fluid producing apparatus, morepreferably, the scraping means is an auger, and a central shaft of theauger is connected to a drive shaft of a drive motor for driving theauger via a universal joint.

In such a low-temperature-slush-fluid producing apparatus, because heattransferred from the drive shaft of the drive motor to the central shaftof the auger is significantly reduced at the universal joint, it ispossible to reduce heat intruding from the drive shaft of the drivemotor into the central shaft of the auger.

In the above low-temperature-slush-fluid producing apparatus, morepreferably, the scraping means is an auger, the auger is configured soas to be rotatable relative to the heat-transfer surface, and both endsof a rotating shaft of the auger are borne by bearings.

In such a low-temperature-slush-fluid producing apparatus, the auger canbe rotated in a stable manner, so that the particle size of theparticles of the low-temperature fluid scraped by the auger can be keptsubstantially constant, and the production efficiency of the slush fluidcan be improved.

A low-temperature-slush-fluid storing facility according to the presentinvention includes the above low-temperature-slush-fluid producingapparatus; transferring means for transferring a low-temperature slushfluid accumulated on the bottom of the container to another place; and alow-temperature-slush-fluid storing tank for storing the low-temperatureslush fluid transferred by the transferring means.

This low-temperature-slush-fluid storing facility allows thelow-temperature-slush-fluid storing tank to be filled with alow-temperature slush fluid with a high weight solidification rate, thusreducing vaporization (boil-off) of the low-temperature slush fluidstored in the low-temperature-slush-fluid storing tank.

More preferably, the above low-temperature-slush-fluid storing facilityis configured so that the low-temperature slush fluid stored in thelow-temperature-slush-fluid storing tank has a desired weightsolidification rate.

In such a low-temperature-slush-fluid storing facility, for example, theparticle size of the particles of the low-temperature fluid produced bythe slush-fluid producing unit or the proportion of the low-temperatureslush fluid transferred by the transferring means to the liquid-phaselow-temperature fluid are adjusted so that the low-temperature slushfluid stored in the low-temperature-slush-fluid storing tank has adesired weight solidification rate.

This reduces the vaporization (boil-off) of the low-temperature slushfluid stored in the low-temperature-slush-fluid storing tank, thusprolonging the storage period.

The present invention provides the advantage of increasing the weightsolidification rate of slush fluid.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic structural diagram of an embodiment of alow-temperature-slush-fluid producing apparatus according to the presentinvention, showing the entire production apparatus.

FIG. 2 is an enlarged sectional view of a relevant part of thelow-temperature-slush-fluid producing apparatus shown in FIG. 1.

EXPLANATION OF REFERENCE SIGNS

1: low-temperature-slush-fluid producing apparatus

2: slush-fluid producing unit

3: cryogenic-fluid generating unit

10: container

11: heat-transfer surface

12: heat exchanger

13: auger (scraping means)

16: rotating shaft (central shaft)

17: bearing

18: bearing

19: drive motor

20: drive shaft

21: universal joint

L: liquid-phase low-temperature fluid

S: low-temperature slush fluid

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of a low-temperature-slush-fluid producing apparatus(hereinafter referred to as a “production apparatus”) according to thepresent invention will now be described with reference to FIGS. 1 and 2.

FIG. 1 is a schematic structural diagram of an entire productionapparatus 1 according to this embodiment. As shown in FIG. 1, theproduction apparatus 1 includes, as main components, a slush-fluidproducing unit 2 for producing a low-temperature slush fluid (forexample, slush hydrogen) and a cryogenic-fluid generating unit 3 forgenerating a cryogenic fluid (for example, gaseous helium at 13 K) to besupplied to the slush-fluid producing unit 2. FIG. 2 is an enlargedsectional view of a relevant part of the slush-fluid producing unit 2.

The cryogenic-fluid generating unit 3 includes a cryogenic-fluid storingtank 4 and a flow-rate/temperature adjusting unit 5.

The cryogenic-fluid storing tank 4 stores a liquid-phase cryogenic fluid(for example, liquid helium at 4 K). The cryogenic-fluid storing tank 4is connected (coupled) to a heat exchanger 12 of the slush-fluidproducing unit 2 through a cryogenic-fluid supplying pipe 14.

The flow-rate/temperature adjusting unit 5 includes a heater 6 disposedsomewhere along the cryogenic-fluid supplying pipe 14 to heat and gasify(vaporize) the liquid-phase cryogenic fluid supplied (pumped) from thecryogenic-fluid storing tank 4; a first valve 7 disposed in thecryogenic-fluid supplying pipe 14 upstream of the heater 6 to adjust theflow rate of the liquefied cryogenic fluid flowing from thecryogenic-fluid storing tank 4 to the heater 6; and a second valve 8disposed in the cryogenic-fluid supplying pipe 14 downstream of theheater 6 to adjust the flow rate of a gaseous cryogenic fluid (forexample, gaseous helium at 13 K) flowing from the heater 6 to the heatexchanger 12 of the slush-fluid producing unit 2.

The slush-fluid producing unit 2 includes a container 10 storing aliquid-phase low-temperature fluid (for example, liquid hydrogen at 13.8K) L; the heat exchanger 12, which is disposed inside the container 10and has a cylindrical heat-transfer surface 11; and an auger (scrapingmeans) 13 for scraping (shaving) a solid-phase low-temperature fluid(for example, solid hydrogen), though not shown, formed on the surfaceof the heat-transfer surface 11.

The container 10 is accommodated in a thermally insulated vacuum vessel(not shown) in which a vacuum is maintained and which has aradiation-shielding plate (not shown), such as a copper plate, laminatedon the inner surface thereof, so that heat intruding from the outside ofthe container 10 into the inside thereof can be reduced.

The cryogenic fluid (fluid having a lower temperature than theliquid-phase low-temperature fluid L stored in the container 10)generated by the cryogenic-fluid generating unit 3 is supplied into theheat exchanger 12. After the cryogenic fluid supplied into the heatexchanger 12 forms a solid-phase low-temperature fluid L on the surfaceof the heat-transfer surface 11 through heat exchange with theliquid-phase low-temperature fluid L stored in the container 10, thecryogenic fluid is temporarily stored in a storage tank (not shown)through a cryogenic-fluid return pipe 15, is liquefied by a liquefyingunit (not shown), and is returned to the cryogenic-fluid storing tank 4of the cryogenic-fluid generating unit 3.

Referring to FIG. 2, the auger 13 is a cylindrical member that includesa rotating shaft (central shaft) 16 whose ends are borne by bearings 17and 18 and that is accommodated so as to be rotatable along theheat-transfer surface 11, having a blade 13 a formed on the outercircumferential surface thereof (that is, the surface opposite theheat-transfer surface 11) spirally in the longitudinal direction.

In addition, the rotating shaft 16 is connected (coupled) to a driveshaft 20 (see FIG. 1) extending from a drive motor 19 (see FIG. 1) via auniversal joint 21 so that, as the drive motor 19 rotates, the auger 13rotates similarly along with that rotation (in the direction indicatedby the arrow in FIG. 1 (clockwise as viewed from the top of FIG. 1)).The blade 13 a of the auger 13 scrapes the solid-phase low-temperaturefluid formed on the heat-transfer surface 11 to form particles 22 of thelow-temperature fluid L (for example, particles of solid hydrogen),which fall onto the bottom of the container 10 and form a slush fluid(for example, slush hydrogen) S.

In addition, the heater 6, the first valve 7, the second valve 8, andthe drive motor 19 are connected to a controller, though not shown, thatcontrols the particle size of the particles 22 of the low-temperaturefluid L (for example, particles of solid hydrogen) scraped by the blade13 a of the auger 13 to a desired size (for example, 1 to 10 μm).

In the production apparatus 1 according to this embodiment, the particlesize of the particles 22 of the low-temperature fluid L scraped by theblade 13 a of the auger 13 can be reduced (finer particles can beformed) by adjusting (controlling) the amount of heat generated by theheater 6, the degree of valve opening of the first valve 7, the degreeof valve opening of the second valve 8, and the rotational speed of thedrive motor 19, thereby increasing the weight solidification rate(solidification rate) of the slush fluid.

In addition, if such a slush fluid (slush hydrogen with an increasedweight solidification rate) is charged (supplied) into, for example, avehicle hydrogen storage tank installed in a vehicle that runs onhydrogen as a fuel, such as a fuel-cell powered vehicle or ahydrogen-fueled vehicle, it is possible to reduce evaporation ofhydrogen in the vehicle hydrogen storage tank and to improve theutilization efficiency of hydrogen.

In addition, because the rotating shaft 16 of the auger 13 is connected(coupled) to the drive shaft 20 extending from the drive motor 19 viathe universal joint 21, heat transferred from the drive shaft 20extending from the drive motor 19 to the rotating shaft 16 of the auger13 can be significantly reduced at the universal joint 21. This reducesthe heat transferred from the drive motor 19 and the drive shaft 20 tothe rotating shaft 16 and the auger 13.

In addition, because both ends of the rotating shaft 16 of the auger 13are borne by the bearings 17 and 18, the auger 13 can be rotated in astable manner, so that the particle size of the particles 22 of thelow-temperature fluid L scraped by the blade 13 a of the auger 13 can bekept substantially constant, and the production efficiency of the slushfluid can be improved.

Although the amount of heat generated by the heater 6, the degree ofvalve opening of the first valve 7, the degree of valve opening of thesecond valve 8, and the rotational speed of the drive motor 19 areadjusted (controlled) by the controller in the above embodiment, thepresent invention is not limited thereto; these adjustments may bemanually performed.

In addition, although the auger 13 described in the above embodiment isconfigured so as to be rotatable along the heat-transfer surface 11, thepresent invention is not limited thereto; the auger 13 may be configuredso as to be reciprocatable along the heat-transfer surface 11, that is,may be equipped with a reciprocating actuator or an ultrasonic vibratorinstead of the drive motor 19.

More preferably, further provided is transferring means (not shown) fortransferring the low-temperature slush fluid accumulated on the bottomof the container 10 to another place and a low-temperature-slush-fluidstoring tank (not shown) for storing the low-temperature slush fluidtransferred by the transferring means.

This allows the low-temperature-slush-fluid storing tank to be filledwith a low-temperature slush fluid with a high weight solidificationrate, thus reducing vaporization (boil-off) of the low-temperature slushfluid stored in the low-temperature-slush-fluid storing tank.

In a more preferable configuration, the low-temperature slush fluidstored in the low-temperature-slush-fluid storing tank has a desiredweight solidification rate. This can be accomplished by adjusting theparticle size of the particles 22 of the low-temperature fluid Lproduced by the slush-fluid producing unit 2 or by adjusting theproportion of the slush fluid S transferred by the transferring means tothe liquid-phase low-temperature fluid L.

This reduces the vaporization (boil-off) of the low-temperature slushfluid stored in the low-temperature-slush-fluid storing tank, thusprolonging the storage period.

In addition, the term “low temperature” used in the presentspecification refers to −273° C. to minus several tens of degreesCelsius.

1. A low-temperature-slush-fluid producing apparatus comprising: aslush-fluid producing unit that includes a heat exchanger having aheat-transfer surface and disposed in a liquid-phase low-temperaturefluid stored in a container and scraping means for scraping asolid-phase low-temperature fluid formed on a surface of theheat-transfer surface; and a cryogenic-fluid generating unit forsupplying into the interior of the heat-transfer surface a cryogenicfluid having a lower temperature than the liquid-phase low-temperaturefluid stored in the container; and being configured so that the flowrate and temperature of the cryogenic fluid flowing into the interior ofthe heat-transfer surface and the rotational speed or reciprocatingspeed of the scraping means can be adjusted based on the particle sizeof the solid-phase low-temperature fluid scraped by the scraping means.2. The low-temperature-slush-fluid producing apparatus according toclaim 1, wherein the scraping means is an auger, and a central shaft ofthe auger is connected to a drive shaft of a drive motor for driving theauger via a universal joint.
 3. The low-temperature-slush-fluidproducing apparatus according to claim 1, wherein the scraping means isan auger, the auger is configured so as to be rotatable relative to theheat-transfer surface, and both ends of a rotating shaft of the augerare borne by bearings.
 4. A low-temperature-slush-fluid storing facilitycomprising the low-temperature-slush-fluid producing apparatus accordingto claim 1; transferring means for transferring a low-temperature slushfluid accumulated on the bottom of the container to another place; and alow-temperature-slush-fluid storing tank for storing the low-temperatureslush fluid transferred by the transferring means.
 5. Thelow-temperature-slush-fluid storing equipment according to claim 4,configured so that the low-temperature slush fluid stored in thelow-temperature-slush-fluid storing tank has a desired weightsolidification rate.
 6. The low-temperature-slush-fluid producingapparatus according to claim 2, wherein the scraping means is an auger,the auger is configured so as to be rotatable relative to theheat-transfer surface, and both ends of a rotating shaft of the augerare borne by bearings.
 7. A low-temperature-slush-fluid storing facilitycomprising the low-temperature-slush-fluid producing apparatus accordingto claim 2; transferring means for transferring a low-temperature slushfluid accumulated on the bottom of the container to another place; and alow-temperature-slush-fluid storing tank for storing the low-temperatureslush fluid transferred by the transferring means.
 8. Alow-temperature-slush-fluid storing facility comprising thelow-temperature-slush-fluid producing apparatus according to claim 3;transferring means for transferring a low-temperature slush fluidaccumulated on the bottom of the container to another place; and alow-temperature-slush-fluid storing tank for storing the low-temperatureslush fluid transferred by the transferring means.
 9. Thelow-temperature-slush-fluid storing equipment according to claim 7,configured so that the low-temperature slush fluid stored in thelow-temperature-slush-fluid storing tank has a desired weightsolidification rate.
 10. The low-temperature-slush-fluid storingequipment according to claim 8, configured so that the low-temperatureslush fluid stored in the low-temperature-slush-fluid storing tank has adesired weight solidification rate.